The invention relates to an adjustable brace comprising a pair of resilient elements which are interconnected at the ends. The brace may be made of plastics, metal or a combination of such or corresponding materials, there being achieved a desired spring effect relative to the thickness of the material.
The field of use is preferably for braces which are to extent behind the ear to hold a loudspeaker, side bars of a pair of glasses, etc. which are to be adapted to an individual anatomy.
The problem of adjusting a side bar of a pair of glasses or an earpiece for a headset for ears of different sizes has been dealt with in prior art solutions in a variety of ways. For earpieces for headsets, one solution has been to have several differently sized xe2x80x98modelsxe2x80x99 to cover the spectrum of ear sizes. This solution has the drawback that it requires a variety of nearly identical parts to be delivered to each customer, none of which is guaranteed to fit exactly, which is an inadequate solution and an obvious waste of material. Another solution uses curved pieces that may be prolonged to embrace a larger part of the ear, maintaining the same radius of curvature. This has the drawback that it may not necessarily be possible to adjust the piece to an appropriate squeeze of the ear in question. Yet another solution uses deformable curved pieces, e.g. a metal wire embedded in a plastics material. This solution has the drawback of being susceptible to wear in that the metal wire may break, destroying its functionality and further not being easily adjusted to an appropriate squeeze of the ear.
The object of the invention is to provide a brace having adjustment means allowing the brace to curve more or less and to assume the shape which is optimum for a given individual. Other fields of use may also be relevant.
This object is achieved in that the elements of the brace are curved so that one element is predominantly positioned externally in the brace, while the other element is predominantly positioned internally in the brace, means being provided to cooperate with both elements between the ends thereof to adjust the distance between the elements.
Preferably, the elements are evenly curved, the external element generally having smaller radii of curvature than the internal element. In this situation it is easier to explain what is meant by the internal and external elements, as the external element will mainly define the convex contour of the brace, while the internal element will mainly define the concave contour of the brace. This mutual position of the elements means that if these are e.g. affected in a direction toward each other, e.g. halfway along the brace, then tensile forces will be generated in the internal element and compressive forces in the external element. When these forces are combined by the parallelogram of the forces at the ends of the brace, the resulting force will cause the brace to curve additionally.
The elements may converge toward one end of the brace and the greater the mutual angle formed by the elements, the greater the effective force of curvature will be. The elements may also diverge, and in this case they will be mutually rigidly connected via a transverse member, so that the moment generated by the tensile and compressive forces also contributes to curving the brace.
When the elements converge at one end of the brace and diverge at the other end of the brace, the distance between the elements will generally increase from one end to the other end of the brace, which is particularly expedient if the adjustment means are either a ring surrounding the elements, or a slide positioned between the elements for cooperation with these.
However, nothing prevents the use of a ring or a slide in connection with an element which converges at both ends, but the curvature effect will be greatest when the slide is in a central position and smallest in an arbitrary one of the outer positions. An adjusting screw may be used as an alternative.
The brace may be made of any suitable material. Important for the functionality of the brace is that a certain rigidity of the junctions between the longitudinal members is ensured and at the same time that a certain flexibility allowing the longitudinal members to be deformed in a direction normal to their longitudinal axis is incorporated. This may be achieved by an appropriate choice of materials in combination with the actual design of the device.
It is noted that the spring constant of the resilient elements need not be the same in the entire longitudinal direction of the element, but may vary so that the way in which the brace curves because of the adjustment means, may be adapted to the anatomic conditions. The brace may also be provided with more than one adjustment means, and these may be adapted for temporary fixing, so that a user may adjust his brace once for all so that it maintains its original shape.
A special embodiment of the invention implements the earpiece in acetal (POM). The advantages hereof, in addition to providing the relevant material properties such as stiffness and surface friction are, low weight, low cost, ease of manufacture in suitable forms and suitability for being adapted to the specific local shapes of the xe2x80x98surroundingsxe2x80x99 of the ear, allowing identical pieces to be used on the left as well as the right side.